The metabolism and mechanisms of activation of the environmental carcinogens N-nitrosopyrrolidine, N-nitrosomorpholine, and N-nitrosodiethanolamine are being investigated. These studies are focused on the identification of electrophilic metabolites and of carcinogen DNA adducts derived from the three nitrosamines. The DNA adducts are thought to arise from metabolic alpha-hydroxylation. This hypothesis is being tested by comparison of synthetic marker compounds with those formed in vitro and in vivo during carcinogen-DNA binding. The effects on metabolism and activation of environmental modifiers and potential inhibitors of carcinogenesis are also being studied.